Over the course of U. S. history, the federal system has become increasingly "nationalized" in the sense that the federal government’s authority has expanded relative to the power of the states. Which factor has been least important in this development?

it provided for selection of government employees through competitive examinations. it also made it unlawful to fire or demote covered employees for political reasons or to require them to give political service or payment, and it set up a civil service commission to enforce the law.

explanation:

use wikipedia, i think they have this.